Auger with Butterfly Flighting

ABSTRACT

An auger for digging holes in soil is coupled to a gearbox and powered by the power take-off of a tractor. The auger comprises a shaft with a cutting head disposed near its bottom end. The cutting head comprises a plurality of cutting (i.e. digging) blades that cut into soil. Flighting disposed above the cutting head moves and lightens soil, but the flighting does not extend far above the cutting head. The majority of the shaft is free from protrusions that may ensnare a user of the auger during use.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/379,223 titled “Auger with Butterfly Flighting,” filed on Sep. 1,2010, the entire contents of which are herein incorporated by reference.This application further claims the benefit of U.S. ProvisionalApplication No. 61/507,146 titled “Post Hole Digger,” filed on Jul. 13,2011, the entire contents of which are herein incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to the field of digging devices,and more particularly relates to an auger for drilling holes.

BACKGROUND AND SUMMARY OF THE INVENTION

A post hole auger for drilling holes in soil is provided. In oneembodiment, the auger is powered by a power take-off (PTO) of a tractor.

Prior art tractor-based post hole augers are generallycontinuous-flighting augers. “Flighting” refers to the helical bladeextending from the rotating shaft of traditional flighted augers.Continuous-flighting augers are efficient at drilling holes because the“flights” move soil up out of a hole as the hole is drilled. However,continuous-flighting auger-based post hole diggers have been the causeof serious accidents and even fatalities due to the flighting on therotating auger shaft catching clothing, hair, or body parts ofindividuals who may be in the digging area.

An auger according to the present disclosure does not have continuoushelical flighting on the auger shaft. The cutting head of the augercomprises a generally flat blade disc with a plurality of cutting bladesaffixed to the disc. An auger tip extends below the disc. A generallybutterfly-shaped flighting extends from the auger shaft and ispositioned above the cutting head, but does not extend continuouslyalong the auger shaft. In operation of the auger, a column of soilaccumulates on a top surface of the flat blade disc for removal from thehole. The flighting “lightens” the column of soil that accumulates toenable a higher column to accumulate on the flat blade disc. Because theflighting is relatively small (in relation to continuous-flightingaugers) and is usually below the ground during post hole diggingoperations, the auger may be less susceptible to accidents caused byflighting on the rotating shaft.

For purposes of summarizing the invention, certain aspects, advantages,and novel features of the invention have been described herein. It is tobe understood that not necessarily all such advantages may be achievedin accordance with any one particular embodiment of the invention. Thus,the invention may be embodied or carried out in a manner that achievesor optimizes one advantage or group of advantages as taught hereinwithout necessarily achieving other advantages as may be taught orsuggested herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be better understood with reference to the followingdrawings. The elements of the drawings are not necessarily to scale,emphasis instead being placed upon clearly illustrating the principlesof the disclosure. Furthermore, like reference numerals designatecorresponding parts throughout the several views.

FIG. 1 is a side plan view of a post hole digger according to anexemplary embodiment of the present disclosure.

FIG. 2 is a bottom perspective view of an auger according to anexemplary embodiment of the present disclosure.

FIG. 3 is a top perspective view of the auger of FIG. 2.

FIG. 4 is an enlarged partial side view of the auger of FIG. 2.

FIG. 5 is a top plan view of the auger of FIG. 2.

FIG. 6 a is a front plan view of the blade mount angle of FIG. 4.

FIG. 6 b is a side plan view of the blade mount angle of FIG. 4.

FIG. 7 a is a front plan view of the blade mount bar of FIG. 4.

FIG. 7 b is a side plan view of the blade mount bar of FIG. 4.

FIG. 8 a is a front plan view of the blade of FIG. 4.

FIG. 8 b is a side plan view of the blade of FIG. 4.

FIG. 8 c is front plan view of an alternative embodiment of the blade ofFIG. 4.

FIG. 9 is bottom plan view of a blade disc according to an exemplaryembodiment of the present disclosure.

FIG. 10 is a bottom plan view of the auger of FIG. 2.

FIG. 11 is an enlarged partial side plan view of the auger of FIG. 2,rotated about 90 degrees from the view of FIG. 4.

FIG. 12 is a cross sectional view of the auger of FIG. 12, taken alongsection lines A-A of FIG. 11.

FIG. 13 is a cross sectional view of the auger of FIG. 11, taken alongsection lines B-B of FIG. 11.

FIG. 14 is a cross-sectional view of the auger of FIG. 5, taken alongsection lines C-C of FIG. 5

FIG. 15 is a side plan view of a coupling for the auger according to anembodiment of the present disclosure.

FIG. 16 is a detail drawing of a flight according to an embodiment ofthe present disclosure.

FIG. 17 is a side plan view of a post hole digger showing an augeraccording to an embodiment of the present disclosure.

FIG. 18 is a side plan view of the post hole digger of FIG. 17, duringoperation of the auger in digging a hole.

DETAILED DESCRIPTION

FIG. 1 is a side plan view of a post hole digger 5 according to anexemplary embodiment of the present disclosure. The digger 5 is showninstalled on a tractor 7 and is used to dig generally-cylindrical holes(not shown) in the ground 8, for example, holes for fence posts. Thedigger 5 is disposed at the rear of the tractor 7 between the rearwheels 9 (only one of which is illustrated).

The digger 5 comprises an auger 10 for drilling into the ground 8. Theauger 10 is supported by a top support arm 6 that extends from thetractor 7 as further discussed herein. A rotating shaft 2 extends from aPTO shaft (not shown) of the tractor 7 and translates rotation from thePTO shaft to a gearbox 4, and ultimately to the auger 10. A shield 3covers moving parts (not shown) that can pose a safety hazard to users(not shown) of the digger 5.

The auger 10 comprises a cutting head 12 rigidly mounted to a rotatableshaft 11. The shaft 11 extends downwardly from the gearbox 4, which isconnected to the tractor's PTO (not shown) via the rotating shaft 2 inthis embodiment. The PTO, rotating shaft 2, and gearbox 4 translaterotation to the shaft 11, which turns the cutting head 12. The shaft 11comprises a generally hollow tube in the illustrated embodiment.

FIG. 2 is a bottom perspective view of the auger 10 of FIG. 1. Thecutting head 12 comprises a blade disc 13 which comprises a plurality ofblades 14. The blades 14 extend from the blade disc 13 downwardly and atan angle such that the rotation of the blade disc 13 causes the blades14 to dig into soil (not shown) during operation of the auger 10. Theblade disc 13 is a generally flat, generally circular disc with one ormore openings 21 along its outer edge 23.

An auger tip 15 is removably affixed to the shaft 11 at a lower end ofthe shaft 11 beneath the cutting head 12. The auger tip 15 comprises agenerally conical extension 17 with one or more blades 16. The auger tip15, conical extension 17 and blades 16 are cast as one piece ofmaterial, such as metal, in the illustrated embodiment. The auger tip 15is removably affixed to the shaft 11 via one or more fasteners 18. Inthis regard, the shaft 11 comprises a through hole (not shown) thatextends through the shaft 11 generally transverse to the shaft 11. Theauger tip 15 fits into the central opening (not shown) of the shaft 11and the fastener 18 is inserted through the through hole of the shaft 11and then through an aligned opening (not shown) that extendstransversely through the auger tip.

The auger 10 further comprises flighting 70 that is rigidly affixed tothe shaft 11. The flighting 70 comprises flights 71 and 72, each ofwhich extends helically around the shaft, as further defined herein. Inthe illustrated embodiment, flights 71 and 72 are substantially similar,and are affixed to the shaft 10 by welding, as further discussed herein.The flighting supports the soil (not shown) that is removed from a hole(not shown) during operation of the auger 10.

FIG. 3 is a top perspective view of the auger 10 of FIG. 1. The bladedisc 13 comprises a top surface 24 that is generally flat. The topsurface 24 receives soil (not shown) that is removed from the earth (notshown) via the blades 14.

The blades 14 are disposed outwardly (in a radial direction) from theshaft 11. The blades 14 are removably affixed to a mounting bracket 19that is rigidly affixed to the blade disc 13. One or more fasteners 20affix the blades 14 to the mounting bracket 19. The blades 14 areremovable and replaceable when worn or damaged. The illustratedembodiment shows an auger 10 with two (2) blades 14. Other embodimentsof the auger 10 may comprise more or fewer blades 14.

In operation of the auger 10, the shaft 11 rotates in the directionindicated by directional arrow 68. The blades 14 are oriented facingopposite directions, but both cut (i.e., dig into the soil) in the samedirection due to this rotation of the shaft 11.

The blades 14 are disposed within the openings 21 (FIG. 2) of the bladedisc 13. In operation of the auger 10 in digging a hole (not shown),shaft 11 rotates, causing the cutting head 12 and auger tip 15 torotate. The auger tip 15 enters the soil and loosens it with its blade16. The blades 14 push soil up onto the top surface 24 of the bladedisc. A column (not shown) of soil accumulates on the blade disc 13until the blade disc 13 is removed from the hole. The flighting 70supports and lightens the soil and allows a larger column of soil toaccumulate than if there were no flighting 70.

FIG. 4 is an enlarged partial side view of the auger 10 of FIG. 1. Inthe illustrated embodiment, the mounting bracket 19 comprises a blademount angle 27 that is rigidly affixed to the blade disc 13. The blademount angle 27 comprises an L-shaped section of angle iron welded to theblade disc 13 in one embodiment.

The mounting bracket 19 further comprises a blade mount bar 26 that isrigidly affixed to the blade mount angle 27. The blade mount bar 26comprises a short, generally flat bar that is welded to the blade disc13 in one embodiment. The blade mount bar 26 comprises one or moreopenings (not shown) for receiving fasteners 20 for releasably attachingthe blades 14 to the mounting bracket 19.

The blade 14 is mounted to the blade disc 13 at a downward-sloping anglewith its bottom edge 25 facing downward. In the illustrated embodiment,the blade 14 angles downward at an angle of about 45 degrees. In otherembodiments, the blade may be differently angled. The blades 14 areaffixed to the blade disc 13 within the openings 21 such that bottomedges 25 of the blades 14 extend within the openings 21.

The blade 14 comprises an angled blade surface 29. During operation ofthe auger 10, soil (not shown) removed by the blade 14 passes up theblade surface 29 and is deposited onto the top surface 24 of the bladedisc 13. Soil accumulates on the top surface 24 and forms a column ofsoil (not shown) as the auger 10 digs into the ground (not shown). Whenthe auger 10 is removed from the drilled hole (not shown), the column ofsoil is removed from the auger by rotating the auger, thus applyingcentrifugal force to the soil.

The flights 71 and 72 are rigidly affixed to the shaft 11 at angles tothe shaft 11, as illustrated. The flight 71 is disposed at an angle Θ tothe flight 72. In the illustrated embodiment, the angle Θ is generally40 degrees. The angle between a horizontal line (indicated by referenceline 74) and the flights 71 and 72 is Θ/2, as each of the flights 71 and72 are generally equidistant from the horizontal 74.

The flights 71 and 72 move and/or lighten soil as it accumulates on thetop surface 24 of the blade disc 13. In this regard, each flight 71 and72 comprises a lower end 75 a and 75 b, respectively and an upper end 76a and 76 b, respectively. The soil moves from the lower ends 75 a and 75b upwardly to upper ends 76 a and 76 b and continues to accumulate in acolumn as described herein until the auger 10 is removed from the hole.

In the illustrated embodiment, the upper ends 76 a and 76 b are disposedat substantially the same level as one another, i.e., are disposed in agenerally horizontal plane. Similarly, the lower ends 75 a and 75 b aredisposed in the same generally horizontal plane.

Outer edges 23 of the disc 13 are generally aligned with an outer edge73 of the flights 71 and 72, as indicated by reference lines 79, inorder to form a uniform generally cylindrical hole in operation of theauger.

In the illustrated embodiment, the auger 10 comprises the two (2)flights 71 and 72. Other numbers of flights may be used in otherembodiments without departing from the scope of the invention.

Note that the auger tip 15 illustrated in FIG. 4 has a single helicalblade 99 that is different from the plurality of blades 16 illustratedin FIG. 2. Any of a number of types of blades may be employed on theauger tip 15 without departing from the scope of the present disclosure.

FIG. 5 is a top plan view of the auger 10 of FIG. 2 showing theflighting 70. Each of the flights 71 and 72 has a generallysemi-circular outer edge 73 when viewed from the top as shown. Theflights 71 and 72 are “clocked” generally 180 degrees from each otheraround the shaft 11. In this regard, the upper ends 76 a, 76 b of theflights 71 and 72 are substantially 180 degrees apart, and the lowerends 75 a, 75 b of the flights 71 and 72 are substantially 180 degreesapart.

Further, each of the flights extends generally 180 degrees+“α” aroundthe shaft 11, where α is the angle that the lower end 75 a of the flight71 overlaps the upper end 76 a of the flight 72. (Note that α ismeasured from a reference line 69 tangential to the lower end 75 a andpassing through the center of the shaft 11.) Similarly, α is also theangle that the lower end 75 b of the flight 72 overlaps the upper end 76b of the flight 71. Thus each of the flights 71 and 72 extendscircumferentially at least 180 degrees around the shaft 11. However, αis typically less than 90 degrees, and in an exemplary embodiment issubstantially 70 degrees. Therefore, the flights 71 and 72 do not extendbeyond 270 degrees around the shaft 11 in the exemplary embodiment. Inother words, the flighting is distinguishable from “continuous”flighting that extends continuously around a shaft for 360 degrees ormore.

FIG. 6 a is a front plan view of the blade mount angle 27 of FIG. 4. Theblade mount angle 27 is rectangular when viewed from the front asillustrated. In one embodiment, the blade mount angle 27 is 3.75 incheswide by 2.5 inches high.

FIG. 6 b is a side plan view of the blade mount angle 27 of FIG. 4. Theblade mount angle 27 is generally L-shaped when viewed from the side asillustrated. In one embodiment, the blade mount angle 27 is 2.5 inchesdeep and is formed from ⅜ inch thick angle iron. The blade mount angle27 has a rear surface 36 that is generally flat, a bottom surface 40that is generally flat, a front surface 38 that is generally flat, and atop surface 39 that is generally flat. The rear surface 36 is generallyperpendicular to the bottom surface 40 and forms an “L” shape inconjunction therewith. The front surface 38 is generally perpendicularto the top surface 39 and forms a general “L” shape in conjunctiontherewith.

FIG. 7 a is a front plan view of the blade mount bar 26 of FIG. 4. Theblade mount bar 26 is a generally flat, generally rectangular bar, andin one embodiment is 2.5 inches high by 3.75 inches wide, and is formedfrom ⅜ inch steel. The blade mount bar 26 comprises one or more openings37, which openings 37 receive the fasteners 20 (FIG. 4) for removablyaffixing the blade 14 (FIG. 4) to the blade mount bar 26.

FIG. 7 b is a side plan view of the blade mount bar 26 of FIG. 4. Theblade mount bar 26 comprises a front side 44 that is generally flat. Theblade mount bar 26 further comprises a rear side 43 and top and bottomsides 45 and 46, respectively. The top side 45 forms a corner 41 inconjunction with the rear side 43. The bottom side 46 forms a corner 42in conjunction with the rear side 43.

FIG. 8 a is a top plan view of the blade 14 of FIG. 4. One embodiment ofthe blade 14 is somewhat rectangular in shape, with a top generallystraight side 48 that is generally parallel to the bottom edge 25. Agenerally straight right side 49 is generally perpendicular to andextends between the top side 48 and the bottom edge 25. A left side 51comprises straight portions 58 and 57 that join together via a curvedportion 59. The straight portions 58 and 57 are generally parallel tothe right side 49. Further, the straight portion 58 is spaced apart fromthe straight portion 57, such that the bottom portion of the blade 14 iswider than the top portion of the blade, i.e., the distance betweenright side 49 and portion 58 is greater than the distance between theright side 49 and the portion 57. In the illustrated embodiment, theblade 14 is about 4.5 inches wide by 4.25 inches tall, and is formedfrom V2 inch thick steel.

The blade 14 further comprises a plurality of openings 47 that extendthrough the blade 14. The openings 47 receive the fasteners 20 (FIG. 4)that removably affix the blade 14 to the blade mount bar 26 (FIG. 4).The openings 47 are countersunk in the illustrated embodiment.

FIG. 8 b is a side plan view of the blade 14 of FIG. 4. The blade 14comprises a generally flat top side 54 and a generally flat bottom side53. The top side 54 is generally parallel to the bottom side 53. Anangled blade portion 55 extends from the bottom side 53 to the top side54 and terminates in a sharp bottom edge 25 at the bottom tip of theblade 14.

FIG. 8 c is a front plan view of an alternative embodiment of a blade140. In this embodiment, the blade 140 is trapezoidal in shape, with atop side 148 and bottom edge 125 substantially parallel to each other,and a right side 149 and a left side 151 at an angle to each other thatis greater than zero. In this embodiment, there are no offset portions57 and 58 (FIG. 8 a), such that side the left side 151 is a generallystraight line that is a mirror image of the right side 149. Further,this embodiment of the blade 140 is formed from 1/2 inch thick steel.

FIG. 9 is bottom plan view of a blade disc 13 according to an exemplaryembodiment of the present disclosure. In this embodiment, the blade disc13 has two curved edges 31 that are partially circular. In this regard,the blade disc 13 is partially circular with irregularly-shaped openings21 a and 21 b in two places along its outer, circular edge 23. (Thecircular edge 23 is shown in broken lines where material has beenremoved to create the openings 21 a and 21 b.) In one embodiment, theblade disc 13 is formed from a 12 inch diameter circular steel platethat is ⅜″ thick.

The two openings 21 a and 21 b are substantially similar and aredisposed 180 degrees apart on the blade disc 13 in the illustratedembodiment. Other embodiments may utilize more or fewer openings 21 aand 21 b, and the openings 21 a and 21 b may be differently spaced.

The opening 21 b comprises a straight wall 32 that is generally parallelto the y-axis of FIG. 8. A straight wall segment 33 is generallyperpendicular to the straight wall 32. The blade mount angle 27 (FIG. 4)is rigidly affixed to the wall 32. In this regard, the rear surface 36(FIG. 5 b) of the blade mount angle 27 is welded to the wall 32.

The opening 21 b further comprises a radial wall 34 that in theillustrated embodiment is aligned radially with the center of the bladedisc 13 at an angle of 45 degrees from the wall 32. A short curved wallsegment 35 extends between the straight wall segment 33 and the radialwall 34.

The blade disc 13 comprises a central opening 30 centrally located onthe blade disc 13. The central opening 30 receives the shaft 11, thus isslightly larger than the shaft 11. The central opening is 2 and 17/32inches in diameter in one embodiment, but may be sized differently inother embodiments. In the illustrated embodiment, the shaft 11 isaffixed to the blade disc 13 by welding.

FIG. 10 is a bottom plan view of the auger 10 of FIG. 1. The fastener 18passes through the opening (not shown) in the auger tip 15 and theopening (not shown) in the shaft 11 and releasably attaches the augertip 15 to the shaft 11.

The rear surface 36 of the blade mount angle 27 is rigidly affixed tothe straight wall 32 of the blade disc 13, such that the blade 14extends into the opening 21 b. Further, the straight portion 58 of theleft side 51 (FIG. 8 a) of the blade 14 extends towards the auger tip15. Note that the blades 16 extend outwardly of the left side 51 of theblade 14 such that there is no “gap” between the blades 16 of the augertip 15 and the blades 14, in this embodiment.

FIG. 11 is an enlarged partial side plan view of the auger 10 of FIG. 4,rotated about 90 degrees from the view of FIG. 4. The fastener 18releasably affixes the auger tip 15 to the shaft 11. The fastener may beany type of standard fastener, such as a threaded bolt coupleable with athreaded nut.

In one embodiment the flighting 70 is spaced apart from the blade disc13 by about 8 inches, though other distances may be used in otherembodiments.

FIG. 12 is a cross-sectional view of the auger 10 of FIG. 11, takenalong section lines A-A of FIG. 11. The blades 14 a and 14 b aresubstantially similar and face in opposite directions as shown. Theblades 14 a and 14 b are disposed within the openings 21 a and 21 b ofthe blade disc 13. A plurality of fasteners 20 releasably attaches theblades 14 a and 14 b to the mounting brackets 19 a and 19 b.

FIG. 13 is a cross-sectional view of the auger 10 of FIG. 11, takenalong section lines B-B of FIG. 11. The lower ends 75 a and 75 b of theflights 71 and 72, respectively, are clocked generally 180 degrees fromone another with respect to the shaft 11.

FIG. 14 is a cross-sectional view of the auger of FIG. 5, taken alongsection lines C-C of FIG. 5. (The cutting blades 14 and the auger tip 15are not included in this cross-sectional view.) A coupling 19 isreceived by and rigidly affixed to an upper end 80 of the shaft 11. Inthis regard, the shaft 11 is generally cylindrical and generally hollowand the coupling 19 is generally cylindrical and generally hollow. Anouter diameter of the coupling 19 is smaller than the inner diameter ofthe shaft 11 such that the coupling 19 fits within the shaft 11. Thecoupling 19 is affixed to the shaft 11 by welding in the illustratedembodiment.

FIG. 15 is an enlarged side plan view of the coupling 80 of FIG. 14. Thecoupling 80 comprises a body 91 with cylindrical walls that fit withinthe shaft 11 (FIG. 14) as discussed above. The coupling 80 furthercomprises a shoulder 88 on its upper end. The shoulder 88 is larger indiameter than the body 91 and fits against the upper end 80 (FIG. 14) ofthe shaft 11. Female threads 87 inside the coupling 80 mate with malethreads (not shown) on a shaft (not shown) on the gearbox 4 (FIG. 1).The shoulder 88 is generally smooth and generally cylindrical with noprotrusions that the user (not shown) could get caught on in use of theauger 10 (FIG. 1). The coupling 80 comprises a chamfered edge 89 whichtransitions to a top surface 92 of the coupling 80.

FIG. 16 is a front plan view of the flight 71 of FIG. 2 before theflight 71 is rigidly affixed to the shaft 11 (FIG. 1). The flight 71 hasan outer edge 73 that curves smoothly from an upper end 76 a to a lowerend 75 a. The upper end 76 a comprises a corner 84 that is coextensivewith a generally straight trailing edge 93. The trailing edge 93 extendsradially from the shaft 11, when the flight 71 is affixed to the shaft11. The trailing edge 93 extends between the corner 84 and a curvedcorner 83 that transitions smoothly to a large curve 85 that extends atleast 180 degrees and transitions to a smaller curve at the lower end 75a before terminating at a corner 86.

The corners 84 and 86 are adjacent to the shaft 11 when the flight 71 isinstalled on the shaft 11. An inner surface 82 is semi-circular toconform to an outer surface (not shown) of the shaft 11. A generallysemi-circular central opening 81 in the flight 71 is defined by theinner surface 82 and the corners 84 and 86. The opening 81 receives theshaft 11 when the flight 71 is affixed to the shaft 11.

The flight 72 is substantially similar to the flight 71. The flights 71and 72 are both formed from a generally flat plate of 10 gauge steel inthe illustrated embodiment, though other materials and sizes may be usedin other embodiments. The flights 71 and 72 are rigidly affixed to theshaft 11 (FIG. 1) by welding in the illustrated embodiment.

FIG. 17 is a side plan view of a post hole digger 50 according to anembodiment of the present disclosure, before the auger 10 begins digginginto the ground 8. The length of the auger 10 in this embodiment is“Ls,” and the distance above the flighting 70 is “Lt.” Importantly, theshaft 11 above the flighting 70 is substantially free of protrusionsthat can potentially harm a user (not shown) in operation of the auger10.

In an exemplary embodiment, Ls is approximately 39 inches and Lt isapproximately 26 and 13/16 inches. The ratio of Lt to Ls, or Lt/Ls, is0.6875. Ideally the ratio of Lt/Ls should be ⅔ or greater, to provide ashaft that is substantially free from protrusions.

FIG. 18 is a side plan view of the post hole digger 50 of FIG. 17 whilethe auger 10 is digging a hole 170. (The soil removed from the hole 170is not illustrated.) There are no extensions or protrusions between thegearbox 4 and the flighting that the user can get caught on. Therefore,once the flighting 70 is beneath the soil 8, the user is safe from thatrisk.

What is claimed is:
 1. An auger comprising: a cylindrical shaft; anupper end coupled to a gearbox and rotatable by a power take-off of atractor; a cutting head disposed near a lower end of the shaft, thecutting head comprising a plurality of blades, the blades extendingdownwardly and angularly from a blade disc, the blade disc comprising anopening associated with each blade, the blade angled downwardly into theopening, the cutting head comprising a substantially circular outeredge; an auger tip releasably affixed to and extending beneath the lowerend of the shaft, the auger tip extending substantially parallel to theshaft and comprising at least one boring blade; a plurality of flightsrigidly affixed to the shaft and extending helically around the shaft,the flights disposed above the cutting head and below the upper end, theflights comprising substantially flat plates rigidly affixed to theshaft at an angle to the shaft, the flights comprising curved outeredges substantially aligned with the outer edge of the cutting head,upper ends of the flights aligned in substantially a same horizontalplane, lower ends of the flights aligned in substantially a samehorizontal plane, each flight extending more than 180 degrees and lessthan 270 degrees around the shaft.
 2. The auger of claim 1, wherein theshaft comprises a smooth portion above the upper ends of the flights,the smooth portion being substantially free of protrusions.
 3. The augerof claim 2, wherein the ratio of the smooth portion to a length of theshaft from its upper end to its lower end is greater than 66%.
 4. Theauger of claim 1, wherein the upper end of the shaft comprises acoupler, the coupler comprising internal threads mateable to thegearbox.
 5. The auger of claim 1, wherein the upper end of each flightcomprises a substantially straight trailing edge extending radially fromthe shaft and then curving towards the curved outer edge.
 6. The augerof claim 5, wherein the plurality of flights comprises a first flightand a second flight, wherein the first flight is clocked 180 degreesfrom the second flight with respect to the shaft.
 7. The auger of claim6, wherein the trailing edge of the first flight and the trailing edgeof the second flight are aligned with each other and with the center ofthe shaft.
 8. The auger of claim 7, wherein the first flight is angledwith respect to the second flight at an angle of substantially 40degrees.
 9. The auger of claim 1, wherein the plurality of blades in thecutting head are oriented such that they face in the same direction whenthe shaft rotates.
 10. An auger comprising: a cylindrical shaft; anupper end coupled to a gearbox and rotatable by a power take-off of atractor; a cutting head disposed near a lower end of the shaft, thecutting head comprising a plurality of blades, the blades extendingdownwardly from a blade disc, the blade disc comprising an openingassociated with each blade, the blade angled downwardly into theopening, the cutting head comprising a substantially circular outeredge; an auger tip releasably affixed to and extending beneath the lowerend of the shaft, the auger tip extending substantially parallel to theshaft and comprising at least one boring blade; a first flight and asecond flight rigidly affixed to the shaft and extending helicallyaround the shaft, the flights disposed above the cutting head and belowthe upper end, the flights comprising substantially flat plates rigidlyaffixed to the shaft at an angle to the shaft, the flights comprisingcurved outer edges substantially aligned with the outer edge of thecutting head, upper ends of the flights aligned in substantially a samehorizontal plane, lower ends of the flights aligned in substantially asame horizontal plane, each flight extending less than 360 degreesaround the shaft, the first flight clocked with respect to the secondflight at substantially 180 degrees.
 11. The auger of claim 10, whereinthe shaft comprises a smooth portion above the upper ends of theflights, the smooth portion being substantially free of protrusions. 12.The auger of claim 11, wherein the ratio of the smooth portion to alength of the shaft from its upper end to its lower end is greater than66%.
 13. The auger of claim 10, wherein the upper end of the shaftcomprises a coupler, the coupler comprising internal threads mateable tothe gearbox.
 14. The auger of claim 10, wherein the upper end of eachflight comprises a substantially straight trailing edge extendingradially from the shaft and then curving towards the curved outer edge.15. The auger of claim 14, wherein the trailing edge of the first flightand the trailing edge of the second flight are aligned with each otherand with the center of the shaft.
 16. The auger of claim 10, wherein thefirst flight is angled with respect to the second flight at an angle ofsubstantially 40 degrees.
 17. The auger of claim 10, wherein theplurality of blades in the cutting head are oriented such that they facein the same direction when the shaft rotates.